# Mass of an Atom and magnetics problem

1. Apr 13, 2010

1. The problem statement, all variables and given/known data
The mass of an atom can be determined by ionizing it and accelerating it through a known electric field followed by a known magnetic field. The ion’s circular path is then measured. Calculate the mass of a chlorine anion of charge 3.20 x 10-19 C if it follows a circular path of radius 0.862 cm after it has been accelerated through a potential difference of 2.5 x102 V and the exposed to a uniform magnetic field of strength 3.00 T .

2. Relevant equations

3. The attempt at a solution

I don`t even know where to begin. I can calculate the velocity of the atom after it is accelerated. Nut how does knowing the velocity, radius and field strength help me find its mass?
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Apr 13, 2010

### collinsmark

Do you mean the velocity expressed in terms of mass? Please, let us see your work.

The ion moves in a circle. How does centripetal force fit into this?